Durability of enzyme stabilized expansive soil in road pavements subjected to moisture degradation

Abstract

Abstract Expansive soils are problematic and susceptible to ground movements, causing significant damage to overlying structures and reduction of bearing capacity. Geotechnical engineering has long recognized that the moisture variation triggers the expansive nature of soils resulting in its swell and shrinkage. Numerous stabilizing additives have been used to treat expansive soils such as lime, cement and fly ash. However, the use of bio-enzymes as a soil stabilizing agent is not currently fully understood. This study examines the durability performance of the enzymatic stabilization of expansive soils in road pavements subjected to moisture fluctuation. Number of experiments was performed under controlled conditions to investigate the mechanical and hydraulic response of stabilized soils subjected to cyclic moisture degradation at various initial moisture contents covering practical moisture ranges in applicable with road pavements. Results showed that strength of stabilized soils was considerably increased with the addition of enzyme based stabilizer, revealing its ability to maintain the material stiffness over moisture fluctuation. While wetting and drying tests had damaging effects on the UCS, enzyme based stabilization served to preserve soil strength effectively throughout the loading cycles. Results obtained from the mechanical/hydraulics tests were further elaborated using imaging analysis which provides an insight into the mechanism of enzyme based stabilization and the influence of moisture when using this novel stabilization approach. This research will substantially benefit geotechnical applications including cost-effective and sustainable road constructions.